646 THE VEINS 



afterwards along the back of the calf, in company with the external or short 

 saphenous nerve, to about the lower part of the centre of the popliteal space, 

 where it perforates the deep fascia, and, sinking between the two lieads of the 

 gastrocnemius, opens into the popliteal vein. As it passes uj) the calf Ix-tween the 

 superficial and deep fascia, it receives numerous cutaneous veins from the heel, and 

 the outer side and Ixick part of the leg, and communicates at intervals, through 

 transverse or internuiscular branches, with the deep veins (venas comites) accom- 

 })anying the peroneal artery. Just before perforating the deep fascia, it receives a 

 large descending branch from the lower and back part of the thigh, and sends 

 upwards and inwards a communicating vein to the long saphenous. A small 

 offshoot from the inferior sural branch of the popliteal artery accompanies the vein 

 for a short distance down the back of the calf. The short saphenous vein contains 

 from nine to twelve valves. 



II. THE DEEP VEINS OF THE LOWER EXTREMITY 



The deep veins of the lower extremity accompany the arteries, and have 

 received corresponding names. From the foot to the knee there are two veins 

 to each artery. These veins run on either side of the corresponding artery, and 

 communicate at frequent intervals with each other across it. They are known as 

 the vense comites. From the knee upwards there is a single vein to each artery, 

 except at the back of the thigh and in the gluteal region, where there are com- 

 monly two. 



The veins of the foot and leg. — The vena? comites of the internal and ex- 

 ternal plantar arteries, after receiving small veins corresponding to the brandies 

 of these vessels, unite beneath the abductor hallucis muscle to form the vena? 

 comites of the posterior tibial artery. These, again, receive, at the spot where 

 the peroneal artery is given off from the posterior tibial, the vense comites of the 

 peroneal artery, which are formed in like manner by the confluence of the various 

 veins corresponding to the branches of that vessel. Opposite the lower border of 

 the popliteus muscle, the posterior tibial veins unite with the anterior tibial veins, 

 which pass through the upper part of the interosseous meml^rane with the anterior 

 til:)ial artery, to form the popliteal. The anterior tibial veins are the continuation 

 of the venae comites of the dorsal artery of the foot, Avhich, in their turn, are 

 formed by the confluence of the veins accompanying its various branches. The 

 anterior tibial venae comites thus formed run with the anterior tibial artery up the 

 front of the leg, and, after passing through the interosseous membrane along with 

 the artery, join the posterior tibial veins to form a single popliteal. 



All these veins contain numerous valves, and communicate, by means of inter- 

 muscular branches, with the superficial veins. 



The popliteal vein is formed by the confluence of the venae comites of the 

 anterior and posterior til)ial arteries at the lower border of the popliteus, and extends 

 upwards to the opening in the adductor magnus at the junction of the middle and 

 lower third of the thigh, where it changes its name to femoral. It accompanies the 

 ])opliteal artery, lying superficial to it in the whole of its course, and tightly bound 

 down to it by its fascial sheath. At the lower part of the space it is a little internal 

 to the artery, but, crossing the vessel obliciuely as it ascends, lies a little external 

 to it at the upper part of the space. The internal popliteal nerve lies su}>erficial 

 to the vein, being external to it above, then on it, and then a little to its inner side. 

 The popliteal vein contains two or three valves. 



The chief variations of the popHteal are : — (1) It may lie between the artery and the bone. 

 (2) It may be ilnuhle thnmuli a [lait or the whole of the popliteal space. (3) Two veins by fre- 

 quently unitin<? in front and behind the artery may form a kind of plexus around the vessel. 

 (4) It may be shorter than usual in consequence of a high union of the tibial venfe comites. 



The femoral vein, the continuation of the popliteal upwards, extends from the 

 tendinous opening in the adductor magnus to an inch and a half below Poupart's 

 ligament where it joins the profunda vein to form the conuiion femoral vein. In 

 this course its relations are similar to those of the superficial femoral artery. As 



